“Waste materials containing noble metals” refers to waste components, waste residues and waste water, which contain gold, silver, platinum, palladium, rhodium, ruthenium, iridium and other noble metals. The widely sources of raw materials mainly concentrate in minerals, smelting, electronics, electroplate, chemical industry. Because noble metals are rare, difficult to refine and valuable, it has huge economic and social benefits to recycle noble metals from waste materials containing noble metals.
Waste materials containing noble metals originated from electronics mainly are: waste circuit boards (including printed circuit boards, integrated circuit plate), the treatment techniques commonly used comprise: mechanical crush, hydrometallurgy, thermo metallurgy or their combinations. Nevertheless, the recycling process has disadvantages of being energy-wasting, inducing pollution, low-productivity, high-cost, etc.
Chinese patent having a publication number of CN1927480A provided a method for treating electronic wastes, which uses microwave irradiation to rapidly pyrolyze electronic wastes, to separate lead and stannum at reaction temperature 600˜800° C., to separate copper, zinc, silver, nickel at reaction temperature 900˜1500° C. However, this invention described neither the process of how the melted metals break away from electronic components, nor the structure of microwave reactor.
Chinese patent having a publication number of CN200958111Y provided an industrial microwave smelting equipment comprising units of housing, internal furnace, furnace lid, continuously-feeding device, infrared-temperature detector, etc. But the infrared-temperature detector therein was positioned on the top of housing, thus failing to reflect the smelting temperature in the furnace. Moreover, because the utility model was used for reducing and smelting metals, and for cooling residues after the metals were smelted, so it provided a closed-loop water cooling system, thus increasing not only the complexity of structure of microwave smelting equipment, but manufacturing costs. More important, such utility model was used to heat ores and metals directly by mixing waste material with other substances which can absorb microwave, which makes the simple waste material components become complicated; it is not beneficial to separate noble metals.